"Hummingbirds come in a jewel-like assortment of colors and are so dexterous, they can hover still for seconds and fly backward. They also have one of the most diverse avian families in the world, boasting about 350 known species across North and South America. Sunbirds, the prime nectar-feeding birds of the Old World, have fewer than 150.

"But once upon a time, tens of millions of years ago, hummingbirds did zip around the hills and forests of Europe. According to Jim McGuire, it all started about 42 million years ago, when hummingbirds broke away from the swifts, their closest living relatives. McGuire, an integrative biologist at University of California Berkeley, calculated this date by examining genetic variation across living hummingbird species and using that information to piece together an approximate evolutionary timeline.

"The plot, McGuire says, thickens at the 30- to 35-million-year mark. The oldest hummingbird fossils we’ve discovered come from this period—but they aren’t American. Instead, they were unearthed in southeastern Germany.

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"Modern hummingbirds evolved in the Americas around 22 million years ago, according to McGuire’s estimates, but we don’t have any fossils from the West that are older than 10,000 years ago. “We basically have no fossil material we can use” in the New World to figure out how to connect the dots, says McGuire.

"Modern hummingbirds evolved in the Americas around 22 million years ago, according to McGuire’s estimates, but we don’t have any fossils from the West that are older than 10,000 years ago. “We basically have no fossil material we can use” in the New World to figure out how to connect the dots, says McGuire.

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"Until scientists discover more fossils on both sides of the Atlantic, the hummingbird mystery is a tough one to solve. But what we do know about hummingbird evolution so far is fascinating. “Hummingbirds can be very resource-specific in terms of their needs; they evolve relatively quickly into actual separate species that look similar and have different needs and genetics,” says Geoff LeBaron, the Christmas Bird Count director for Audubon."